Self-locking indicator fuse



April 29. 1924.

W. J. MORRISON SELF LOCKING INDICATOR FUSE Filed Feb. 5. 1921 Patented Apr. 29, 1924.

UNITED'OSTATES PATENT OFFICE.

WILLIAM J. MORRISON, OF CHICAGO, ILLINOIS, ASSIGNOR F ONE-HALF TO B. JOSEPH RICE, OF CHICAGO, ILLINOIS.

SELF-LOCKING INDICATOR FUSE.

Application med February 5, 1921. Serial No. 442,621.

To all whom it may concern:

Be it known that I, VVILLTAM J. MORRISON, a citizen of the United States, residin at Chicago, in the county of Cook and tate of Illinois, have invented certain new and useful Improvements in Self-Locking Indicator Fuses, of which the'following is a specification. I

This invention relates to electric fuses and is designed primarily for embodiment in fusesof the capsule or plug type, where the fuse is inserted and electrical connection made by screwing a portion of the fuse into a socket having terminals in the electric circuit to be guarded.

The object of the inventi'onis to provide a fuse which may be readily inserted into a terminal socket but will not be removable therefrom until the fusible link is destroyed, and which will therefore serve as a safeguard against substitution of non-protecting links or connections between the terminalsof the sockets; also to provide a fuse which, while serving the aforesaid purpose, will also act to indicate thefact when the fuse is blown, and thus serve as an indicator fuse.

The invention proceeds upon the principle ofhaving the fuse device constructed in two main parts, namely,a shell which is adapted to be screwed into the socket and carrying contacts in position to impinge against the terminals of the socket, and a fuse carrier that may be readily slipped into the shell in positionto obstruct access to the latter, and automatically interlocked therewith and held against removal therefrom or against withdrawal therefrom by a detent controlled by thefusible link, and without engaging the shell in, a manner to permit the latter to be released from the socket by manipulation of the carrier; resilient means being introduced between the shell and the carrier which normally tends to force them apart and does displace them relatively in an axial direction when the fuse is blow-n in order to indicate the fact; a

The invention will be fully understood upon reference to the accompanying drawings, in 'which Figure 1 is a sectional view of a fuse embodying the several features of the present invention, the section being taken in an axidal plane passing through the fuse duct; an

Figure 2 is a detail view of the detent de vice.

A represents a shell which is composed mainly of a cup A of rigid fiber or other suitable insulating material, with a sur rounding sleeve A of metal fashioned to form a screw threadthrough which tosecure the shell in a terminal socket, and which sleeve is in position to impinge against a conducting portion of the socket serving as a terminal in the circuit to be protected; said shell also having a central contact button A in position to impinge against the other terminal of the socket.

B represents the fuse carrier which is preferably of porcelain or other strong insulating material, formed with a reduced neck B adapted to enter the shell A, with a fuse duct B leading from the periphery of the neck B to the interior of the carrier, and with a central opening B 0 represents a detent mounted on the carrier B in position to engage beneath ashoulder A on the shell A, which is preferably provided by continuingthe metallic sleeve A over the upper edge of the insulating cup A, and which preferably constitutes a continuous annular projection on the inside of the cup. Detent C comprises a dogging member C engaging beneath the shoulder A and bearing members G which are recessed into the neck B on either side of the bore B and adapted to prevent the'detent from tipping out ofposition, particularly under the tension of the fuse link D, but which are connected with the dogging member C with. sufficient resiliency to permit the latter to retire into the fuse bore B :when the carrier is being pushed into the'socket and then snap out again beneath the sh0ulder A to interlock the carrier with the socket. Any construction of detent may be employed so long as it will satisfactorily perform these functions. prevent the carrier from being withdrawn from the shell, but it will permit the carrier B to rotate freely in the shell and thus prevent the shell being unscrewed by manipulation of the carrier.

D represents the fuse link which is secured at one end in the detent C, as, for lnstance,

The detent will by passing it through and heading it in the perforation C in the detent. and which is then threaded up through the fuse bore l3 and passed down through the central opening B where it is secured in taut condition in an anchoring disk E which engages beneath a shoulder B of the carrier B and secures the fuse and, through the fuse, the detent C against displacement. If, however, the fusible link D should be destroyed by an overload of current, detent C is readily released so that it passes down out of the bore B and remains in the shell, thereby permitting the carrier B to be removed.

F represents a spring or other equivalent resilient means interposed between the shell A and the carrier B and constantly tending to displace said members relatii'ely in an axial direction. It is restrained, however, in its action by the detent C acting through fusible link D. Disk E being of conducting material, as are the resilient member F and the button A upon which the resilient member seats, circuit is established through sleeve A detent G, fusible link D, anchoring disk E, resilient member I, and button A between the two terminals of any standard form of socket with which the fuse of the present invention is adapted to be used.

In using the new construction fuse, the shell A will be screwed into the socket independentlv of the carrier B, with the de- Figure 1, and with the resilient member F in place within the shell, the carrier may be put in place by merely thrusting it axially into the socket until the detent G snaps under the annular shoulder A. The device will remain in this condition until link D is destroyed, when the carrier B will be thrust outwardly in the socket A a distance sufficient to indicate the fact that the fuse was blown, and show which one of a group of fuses is the cause of an interrupted circuit. To renew the fusible link it is simply necessary to thread the same through the detent C. draw it tightly up through the fuse duct B and secure it in the anchoring disk E, when the carrier will be ready for reintroduction into the socket.

I claim:

1. In an electric fuse, a shell constructed for removable insertion into a fuse socket and carrying insulated contacts for impingement against the terminals thereof, a carrier for a fusible link constructed for entry into the shell without removal engagement therewith, and a fuse-released detent resisting removal of said carrier.

2. In an electric fuse, a shell constructed for removable insertion into a fuse socket and carrying insulated contacts for impingement against the terminals thereof, a carrier for a fusible link constructed for entry into the shell without removal engagement therewith, a fuse-released detent resisting removal of said carrier, and a spring displacing the carrier in the shell when the detent released.

8. In an electric fuse, a shell constructed for removable insertion into a fuse socket and carrying insulated contacts for impingement against the terminals thereof, a carrier for a fusible link constructed for entry into the shell without removal engagement therewith, a fuse-released detent resisting removal of said carrier, and a spring normally electrically connecting the fuse with one of the terminals of the shell and displacing the carrier in the shell when the detent is released.

at. In an electric fuse, a shell constructed for removable insertion into a fuse socket and carrying insulated contacts for impingement against the terminals thereof, a carrier for a fusible link constructed for entry into the shell without removal engagement there with, and a fuse-released detent resisting removal of said carrier; said detent serving to electrically connect the fuse with one of the terminals of the shell.

5. In an electric fuse, a shell constructed for removable insertion into a fuse socket and carrying insulated contacts for impingement against the terminals thereof, a carrier for a fusible link constructed for entry into the shell without removal engagement therewith, a fuse-released detent resisting removal of said carrier, and a spring displacing the carrier in the shell when the detent is released; said detent electrically connecting the fuse with a terminal of the shell; and said spring normally holding the detent against the terminal.

6. In an electric fuse, a shell adapted for removable insertion into a fuse socket and having an electrically conductive side wall adapted for impingement against a terminal of the socket, a carrier constructed for entry into the shell without removal engagement therewith, a detent electrically contacting with said side wall and interengaging it with the carrier, a fusible link extended from said detent inwardly through a wall of the carrier, an anchoring plate on the interior of the carrier receiving the inner end of the fuse link, and a conductive spring between the shell and said anchoring plate.

7. In an electric fuse, a shell adapted for removable insertion into a fuse socket and having an electrically conductive side wall adapted for impingement against a terminal of the socket, a carrier constructed for entry into the shell without removal engagement therewith, a detent electrically contacting with said side wall and interengaging it with the carrier, a fusible link extended from said detent inwardly through a wall of the carrier, an anchoring plate on the interior of the carrier receiving the inner end of the fuse link, and a conductive spring between the shell and 'said anchoring plate; said shell carrying a contact button against which the spring seats and which is in position to impinge against the other termi nal of the socket.

8. In an electric fuse, a shell having a threaded wall for removable engagement with a fuse socket and having an annular shoulder within it, a carrier constructed for entry into the shell without removal engagement therewith, having a detent adapted to engage said shoulder and interlock the carrier therewith against relative axial displacement while permitting relative rotation etween them, and a fusible link holding said detent to duty.

9. In an electric fuse, a shell adapted for removable insertion into a fuse socket with terminals and comprising an insulating cup having a surrounding metallic sleeve threaded to engage the socket and impinge against one of the terminals, and an annular shoulder of conductive material on the interior of the cup in electrical connection with the sleeve, a carrier constructed for entry into the shell without removal engagement there tation between them, and a fusible link holdingsaid detent to dut 10. In an electric use, a shell having a threaded metallic wall for removable engagement with a terminal in a fuse socket and having within it an annular conducting shoulder in electrical connection with said wall, a carrier constructed for entry into the shell without removal engagement therewith, having a metallic detent adapted to engage said shoulder and interlock the carrier therewith against relative axial displacement while permitting relative rotation between them, a fusible link holding said detent to duty and extending to the interior of the carrier, an anchoring disk sustaining the inner end of the fuse link, and a spring tending to separate said carrier and shell.

Signed at Chicago, Illinois, this 2nd day of February, 1921.

WILLIAM J. MORRISON. 

